1. Field of the Invention
The present invention relates generally to retractable coverings for architectural openings and more particularly to a retractable covering that can be rolled about a roller in the retracted position of the covering with the covering having a top rail and a bottom rail that can be raised or lowered independently to give the covering top down/bottom up capability.
2. Description of the Relevant Art
Coverings for architectural openings have assumed numerous forms for centuries with early forms simply being fabric draped across architectural openings such as windows, doors, archways, or the like. Subsequently, retractable coverings for architectural openings became popular so the covering could be extended across the opening or retracted adjacent one or more sides of the opening. A popular form of a retractable covering for an architectural opening is a venetian blind wherein a plurality of slats are supported on cord ladders with the entire assemblage of slats being movable between an extended position across the architectural opening, wherein the slats are evenly distributed and horizontally disposed, to a fully retracted position where the slats assume a neat stack across the top of the opening. When the venetian blind is extended, the slats can also be pivoted about their longitudinal axes between open and closed positions to permit or block vision through the covering.
Vertical blinds are also a popular form of retractable covering for architectural openings and work very similarly to a venetian blind except where the slats are disposed vertically rather than horizontally. Again, the assembly of slats can be extended horizontally across the opening or retracted into a neat stack adjacent one or more sides of the opening and can also be pivoted about vertical axes when in the extended position between open and closed conditions.
More recently, cellular shades have become popular wherein a plurality of vertically or horizontally disposed cells are interconnected and movable between an extended position across an architectural opening and a retracted position adjacent one or more sides of the opening. Such cellular shades themselves can assume numerous forms such as disclosed in U.S. Pat. Nos. 5,313,999; 5,228,936; and 5,897,731.
In even more recent forms of retractable coverings for architectural openings, a bottom rail positioned along a lower edge of a shade material is reversibly movable vertically to extend or retract the covering but in addition, the top edge of the shade material is secured to a top rail which can also be raised or lowered relative to a head rail. Accordingly, the shade material, which extends between the top rail and the bottom rail, can be extended or retracted to any desired degree between the two rails and also positioned at any location across the architectural opening. This type of retractable covering is commonly referred to as a top down/bottom up covering.
Typically in top down/bottom up coverings, there are independent cord-operated systems for raising and lowering the top and bottom rails so they can be independently positioned at any desired location relative to each other. In such systems, when the rails are moved toward each other, the shade material is gathered between the two rails and when the rails are separated, the shade material extends between the routs.
Rollers have become a common form for retracting coverings for architectural openings with early forms of such rollers being on roll-up shades where a wooden roller simply had the top edge of a flexible sheet of shade material secured thereto and the lower edge had a bottom rail or ballast so when the shade material was unrolled from the wooden roller, it would extend across the architectural opening. A clutch mechanism was connected to the roller so the shade could be raised or lowered to any desired degree and would retain its position.
More recently, more sophisticated roller systems having transmissions and clutches for operation thereof have been utilized in coverings for architectural openings, but a simplified roll-up system for a top down/bottom up shade has been desired.
It is to provide a simplified system for rolling up a top down/bottom up shade that the present invention has been developed.